Electron gun support



June 28, 1960 H. l.. LEvlN A 2,943,227

ELECTRONGUN SUPPORT Filed July 6. 1956 United StatesY ELECTRON GUN SUPPORT Herbert L. Levin, Paterson, NJ., assigner to International Telephone and Telegraph Corporation, Nutley, NJ., a corporation of Maryland Filed July 6, 1956, Ser. No. 596,331

9 Claims. (Cl. S15- 3.5)

Electron discharge devices in kthe nature of traveling? wave tubes and the like have electron gun structures which must be accurately positioned within the tube housing with respect to the centerline of the magnetic field. Further, the electron gun elements which go to make up the electron gun assembly must be accurately positioned with respect to each other, not only when assembled, but when the tube is in operation. Failure to maintain these accuracies produces Vfaultyoperation of the tubes with its inherent distortion and shortened life. A

Traveling-Wave tubes generally comprise two features, namely, a helix for producing a slow electromagnetic lield along the helix with a-corresponding longitudinal electric eld, and an electron beam iiow valong the helix axis at the central portion thereof. Any circuit capable of propagating la slow electromagnetic wave can be ,used as a traveling-wave tube. The circuit most often associated with the traveling-wave tube is the helix, inasmuch as it is easy to construct and Ais al good circuit with high im-V pedance and constantV phase 'velocity over a wide frequency range. However, these advantages are seriously affected when the electron gun is not properly aligned with the helix, i.e., the centerline of the magnetic field.

Therefore, it is one object of this invention to provide an improved electron gun structure for an electron discharge device.

Other objects of this invention are to provide an improved support for electron gun elements; to provide electron gun supports which are compact, easily fabricated, and rugged; to provide electron gun supports which maintain critical alignment and spacing of the gun elements relative to each other and a traveling-wave tube helix; to provide an electron gun support void of cements and brazing materials for supporting the gun elements; and to provide an electron gun support for reducing the electron gun size and allowing lcloser spacing of the gun elements.

Further objects, aspects and advantages of the invention together with the organization and method of operation of the invention may best be understood by reference to the following description taken in connect-ion with the accompanying drawings, wherein:

Fig. 1 shows a ceramic rod, Aaccording to an embodiment of the invention with a plurality of slots cut transverse to the rod axis; v l

Fig. 2 shows a partialsection of a metal type travelingwave tube with the electron gun elements and supports therefor, according to the invention herein; Y

Fig. 3 shows a retainer washer, yuseful in Fig. 2, for positioning the ceramic rod members of Fig. 1;

Figs; 4A and 4B show a retainer washenvuseful Iin Fig. 2 at the opposite extremity from the washer shown in Fig. 3for positioning the ceramic rod members of Fig. 1, Fig.4B being taken along line B-B of Fig. 4A;

i atent g ice Patented June 28, 1960 wave tube with the electron gun elements and supports therefor, according to `another embodiment of the invention;

Fig. 7 shows a partial section of a glass type traveling- Wave tube with the electron gun elements and supports therefor, according to still another embodiment of the invention; and A Fig. 8 s a sectional View taken along line 8 8 of Fig. 7.

Throughout the specification and drawings, wherever it is possible to facilitatea better understanding of the invention, alllike parts and/or members will be given like designation numbers or references.

Now referring in more detail to Figs. 1 and 2, there is shown an insulated rod-like member'l, made preferably from ceramic 'materialor other material havinga very low coeii'icient of expansion, and which'is rugged, durable and highly resistant to heat. The rod 1,`has a series of sequentially spaced slots or grooved portions 3, cut transverse to the rod axis a predetermined depth, the said slots having a thicknessin the axial direction to re-` ceive the edge portions of the electron gun elements. In Fig. 2, a partially sectioned metal envelope 5 is shown and the'electron-gun elements mounted therein according to one embodiment of the invention.

, Theceramic rods 1 are longitudinally positioned in the gun portion of the tube envelope 5 bearing against theY inner cylindrical surface 7 thereof. The rods lare fixed-` ily held in their spatial `relation to each other, in their circuital orbit, by a pair of retainer washer members 9 and 11,'show'n inFigsI 3, 4A'and 4B( The retainer'9, 'is-an annular disc member, preferablyrof metal, having an aperture 13 at its central portion, and threecireularly` notched portions 15 circumferentially spaced in equal de-Y grecs, the notched port-ions being adapted to iixedly en-r gage the ceramic rod members 1. The retainer Ywasher 11 `is an annular disc member, similar to retainer member 9 but with offset portions 17 which partially encompass the ceramic rods, when operatively mounted in the tube envelope, with spring loading by one or more compressive resilient members 19. The retainer Awasher member 11 is mounted to the ceramic rods at their uppermost portions, Whereas the retainer washer member 9.is xedly positioned to partially encompass the lower extremity of the ceramic rod member The electron gun assembly of .the traveling-wave tube, of Fig. 2 comprises a cylindricallyapertured cathode electrode 21, a cylindrically -apertured control grid electrode 23 and an annular accelerating electrode 25, all axially aligned with each of the corresponding electrodes having radially extending anges 27, 29 and 31, respectively, =which flanges slidably engage the slotted portions 3 of the ceramic rod members 1. The depth of the slotted portions 3 determines and fixes the radial positioning of each of the electrodes whereas the longitudinal spacingr of the slots governs the axial positioning of the electrodes in their vertical alignment array. For proper and ,ethcient operation of the tube, the electron gun elements` must be accurately positioned Vboth axially and radially, a'factory which makes 'the type of construction herein contemplated yby this invention very useful and expe! dient. The slotted portions make possible the proper alignment of the respective electron gun elements with respect to each other but also make vlfor Vthe proper concentric valignment of the electron gun elements with respect to the traveling-wave tube `helix 33 and the axis thereof.V Further, the unique slotted features makes for fast 0 and easy mounting of the gun electrodes, together with curate'assembly. vThere is no need here for great skill" the retainer washer member, `to form a compact and acin positioning the elements nor is there any need for the application of cement or brazing to cause the said elements to adhere to the mounting ceramic rods 1, a factor which makes for closer spacing of the elements and a resulting reductionin the size of the electron gun length. The complete electron gun assembly is then simply positioned within the tube envelope 5, fixing the assembly so that the rods lie adjacent the cylindrical inner surface7 of the tube along their respective tangential surfaces, and the rod surface extremities or bases engage the axial reference surface of tu'be member 35. The tube member 35 is an annular member to which is attached `a concentric helix holding device 36 for structurally holding and maintaining the helix 33 in `axial alignment. In this embodiment the member 35 is preferably of magnetic material to function as a flux path. The electron gun `assembly is iixedly heldV in its operative position by the resilient spring members 1,9 which repose between the retainer 17 and the tube stem 37, and compressively causes the rod members of the assembly to ixedly maintain their position within the tube housing.

Fig. 5 shows Aa section through the line 5--5 of Fig. 2, illustrating the circumferential spacing of the rod members 1 and how lthe gun elements repose on the slotted portions 3 of the said rod members. The gun elements are externally connected by means` of leads which connect to the stem pins 39 of stem 37 and are insulated by insulating tube members 41 ywhich extend through cutouts 15A in Washer 11.

Figs. 6 and 7 show other embodiments of the invention wherein glass envelopes are used instead of the metal type shown in Fig, 2. In Fig. 6, the compressive resilient member 43, interposed between the tube stem 45 and rod member 1, directly engages the upper end portion of the rod 1, and causes the said rod and assembly of whichit is a constituent part, to iixedly maintain its position relative to the tube envelope 'and the helix axis thereof. In both Figs. 6 and 7, the base members 35 may be different both in shape `and material to accommodate different type helix members and envelopes, but the positioning 4of the electron gun assembly in each instance is the same, merely setting the assembly within the envelope so that it sets on the base and then applying the resilient members 43 and 43A so that the assembly becomes rigidly xed.

In Fig. 7 one or more of the gun elements such as 46 may be shaped to also serve as a positioning retainer for rods 1. The clement is provided with notched portions 47 to partially encompass the rod and also to be received in the groove 3. j

The resilient compressive elements 19, 43 and 43A may be formed in various shapes and arrangements. For example, the element 19 may be a U-shaped wire or ring and where a ring shape is used it may be corrugated to provide spring action. The element 43 may be cupshaped and include longitudinal slots so that one segment would bear on the end of a rod 1 while adjacent segments engage the sides of the rod for positioning purposes. The element 43A is made of sheet stock, one end of which is turned to clamp onto the stem lead 39 while the other end is kept flat for spring action and providled with flange-like tabs 48 to engage the sides of the ro Although only certain embodiments of the invention have been shown, `the invention is not to be strictly limited thereto. That the electron gun element support members may take on various other type forms, sizes and shapes, e.g. square rods, etc., and that the slot portions may also have various `and other type configurations than that illustrated in the drawings, is obvious. Although in the embodiments herein, a traveling-wave tube is illustrated, the invention is not limited thereto, but other types of electron discharge devices which embody the principle of electron gun structures as herein contemplated may make use of the invention as herein described.

I claim:

l. An electron discharge device comprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, an electrode assembly including at least three insulating rods interposed between said stem reference member and said base reference member and sequentially spaced in a circular array, each of said rods bearing against said reference surface along the entire length of said rods, and a plurality of electron beam forming electrodes disposed in parallel relation to said reference members and mounted on said rods in a predetermined spaced relationship therealong for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, and resilient compressive means interposed between one of said reference members and the adjacent end of each of said rods to xedly position said assembly inY said envelope by forcing the other end of each of said rods to bear against the other of said reference members.

2. An electron discharge device comprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, an electrode assembly including at least three insulating rods interposed between said stern reference member and said base reference member and sequentially spaced in a circular array, each of said rods bearing against said reference surface along the entire length of said rods, and a plurality of electron beam forming `electrodes disposed in parallel relation to said reference members and mounted on said rods in a predetermined spaced relationship therealong for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, and resilient compressive means interposed between said stem reference member and the adjacent end of each of said rods to xedly position said assembly in said envelope by forcing the other end of each of said rods to bear against said base reference member.

3. An electron discharge device comprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, an electrode assembly including at least three insulating rods interposed between said base reference member and sequentially spaced in a circular array, each of said rods bearing against said reference surface along the entire length of said rods, each of `said rods having a plurality of partially grooved portions disposed transversely of the longitudinal axis of said rods, and a plurality of Velectron beam forming electrodes disposed in parallel relation to said reference members and mounted on said rods in a predetermined spaced relation therealong for axial alignmentsaid rods and said reference surface providing radial alignment for said electrodes, said electrodes 'including annular portions, the circumference of said annular portions 4being received in the grooved portions of said rods, and resilient Vcompressive means interposed between one of said `reference members and the adjacent end of each of said rods to iixedly position said assembly in said envelope by forcing the other end of each of said rods to bear against the other of `said reference members.

4. An electron discharge device Vlaccording to claim 3.

Y wherein at least one of said electrodes includes notched portions adapted to partially encompass each of said rods to position each of said rods in said crcular'array.

' 5. An electron discharge devicecomprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stern reference member and bearing against said reference surface, an electrode assembly including at least three insulating rods interposed between said stem reference member and said base reference member and equally spaced in a circular array, each of said rods bearing against said reference surface along the entire length of said rods, each of said rods having a plurality of partially grooved portions disposed transversely of the longitudinal axis of said rods, and a plurality of cylindrically apertured electron beam forming electrodes having radially extending flanges thereon, the flange portions slidably engaging the grooved portions of said rods to position said electrodes in parallel relation to said reference members and in a predetermined spaced relationship along said rods for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, means for iixedly retaining said rods in their equally spaced circular array, and resilient compressive means interposed between said stem reference member and the adjacent end of each of said rods including said ixedly retaining means to xedly position said assembly in said envelope by forcing the other end of each of said rods to bear against said base reference member.

6. A traveling wave tube having a helix comprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of a portion of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, an electrode assembly including at least three insulating rods interposed between said stem reference member and said base reference member and circumferentially spaced equally in a circular array, each of said rods bearing against said reference surface along the entire length of said rods, each of said rods having a plurality of slotted portions in transverse relation to the longitudinal axis of said rods, and a plurality of cylindrical, apertured, electron beam forming electrodes having radially extending flanges thereon, a circumferential portion of said anges slidably engaging said slotted-portions of said rods to mount said electrodes in parallel relation to said reference members and in a predetermined spaced relationship along said rods for axial alignment, said rods and said referl ence surface providing radial alignment of said electrodes with respect to said helix and each other, means for fixedly retaining said rods in their equally spaced circular array, and resilient compressive means interposed between said stern reference member and the adjacent end of each of said rods including said ixedly retaining means to fixedly position said assembly in said envelope by forcing the other end of each of said rods to bear against said base reference member.

7. A support for electron beam forming electron gun electrodes in an electron discharge device comprising a vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, at least three insulating rods interposed between said stem reference member and said base reference member, each of said rods bearing against said reference surface along the entire length of said rods, each of said rods having a pll1=` rality of partially grooved portions in transverse relation to the longitudinal axis of said rods, means including said partially grooved portions for supporting said gun electrodes in parallel relation to said reference members and in a predetermined spaced relationship along said rods for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, means havingspaced recesses therein to engage one end of each of said rods contiguous with said stem reference member and means having spaced recesses therein to engage the other end of said rods in contiguous relation with said base reference member, both of said last-mentioned means xedly positioning said rods and said gun electrodes in said envelope.

8. A support for electron beam forming electron gun electrodes in an electron discharge device comprising a Vacuum envelope, the inner surface of said envelope providing a reference surface lengthwise of Said envelope, a stem reference member disposed transversely of said envelope and bearing against said reference surface, a base reference member disposed transversely of said envelope spaced from said stem reference member and bearing against said reference surface, at least three circularly spaced insulating rods interposed between said stem reference member and said base reference member, each of said rods bearing against said reference surface along the entire length of said rods, each of said rods having a plurality of slotted portions in transverse-relation to the longitudinal axis of said rods, means including for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, said gun electrodes including flanged portions having circumferentially spaced recesses therein to encompass a portion of said rods and engage said slotted portions to fixedly retain the circularly spaced-position of said rods, and resilient compressive means interposed between one of said reference members and the adjacent end of each of said rods cooperating with `said recessed flanges for fxedly positioning said rods and said electrodes in said envelope by forcing the other end of each of said rods to bear against the other of said reference members.

9. A traveling wave electron discharge device comprising an electron gun for projecting a beam of electrons along the longitudinal axis of said device and a helical slow Wave structure disposed in interacting relation with said beam, said electron gun including a portion of the vacuum envelope of said device disposed coaxially of said axis, the inner surface of said envelope providing a reference surface lengthwise of said portion of said vacuum envelope, a stem reference member disposed Y transversely of said portion of said envelope and bearing against said reference surface, a base reference member having an axially disposed aperture for passage of said electron beam disposed transversely of said portion of said envelope spaced from said stem reference member tion to said reference members and mounted on said rods v in a predetermined spaced relationship' therealong for axial alignment, said rods and said reference surface providing radial alignment for said electrodes, resilient compressive means interposed between one of said reference members and the adjacent end of each of said rods to lixedly position said electrodes in said envelope byforcing the other end of each of said rods to bear against the other of said reference members, and said slow wave structure including a helical conductor and a plurality of rods disposed lengthwise of said helical conductor in supporting relation thereto and means mounted on the other surface of said base reference member to support the ends f said last-mentioned rods to position said rods and said helical conductor in a coaxial relation to said beam.

References Cited in the le of this patent UNITED STATES PATENTS ,1,996,731 Whitman 'Apr. 2, 1935 8 Von Ardenne Sept. 21, Flechsig et al. Dec. 12, Bay'ford et al. Feb. 2.0, Ohmart Dec. 7, Weiss Jan. 17, Goodall June 26, Morton ..v Jan. 29, Morton Apr. 30, 

